The Rule of Law states that no man or woman is above the law. The Commonwealth Government cannot enact legislation that exempts its officials' duties to obey the law

The Commonwealth Government is able to pass laws on any matter at all, because of s 109 of the Constitution

The Commonwealth Government may do so, as long as it doesn’t offend against the doctrine of separation of powers 

The Commonwealth Government can do this, but only with the consent of a majority of the State governments, pursuant to the supremacy of parliament doctrine